Working voltage: DC5V Suitable battery: it is suitable for batteries that meet the requirements of stopping discharge voltage of 2.5~3.5V and starting from 2.8V to ~4.2V Discharge current: about 1A non-constant current at most, which is not adjustable and does not support transformation. Charging voltage: controlled by special battery charging chip, the maximum charging time is about 1A, the full charging voltage is 4.2V, and the charging current is less than 0.1A. Instructions for use: 1. Switch channel display: Each channel is and does not interfere with each other. Click the "Channel /CHN" button to switch the display channels, and you can view and set the parameters of each channel. 2. Test the internal resistance: Install the battery, power it on, wait for 10 seconds, and display the test results of battery voltage and internal resistance. This product uses the DC two-wire method to test the internal resistance. Due to the limitation of the test principle, there may be cases where the battery cannot be recognized and the internal resistance is always displayed as 9999. When the battery is not installed, the test loop is open, which is equivalent to infinite resistance, and the internal resistance shows 9999 milliohms. 3. Charging function (not suitable for charging lithium iron phosphate battery): Install the battery in the battery holder, adjust the mode to "charging" mode, and click "Start/Stop /R/S" to run the program; After the charging is completed, the status indication is completed; Record the capacity, energy and charging time during the charging process. The charging capacity is for reference only, please refer to the discharge capacity. Color: Green Material: plastic Package Contents: 1 x 18650 Battery Capacity Internal Resistance Tester Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.